Machine-switching telephone-exchange system



Aug. 7, R93.

R. L. STOKELY MACHINE SWITC HING TELEPHONE EXCHANGE SYSTEM 8 2 v 0 N d e l i F RAY L. STOKELY, 0.;

VTESTEBN ELECTRIC RATION OI? HER/V YORK.

FEDERAL GIiTPl-LNY, INCOBPQEA ANK], NEW YORK, ASSZG-NOR T0 0?? NEW YOi Id. 2., A CORPO- llt-TAUHLD].E-QWiClUiiLING TELbiriGNE-E. CIIALGE SYSTEM;

implication filed I lovember 38, 1919. serial No. 341,104.

To all LD/lOWZ- it may concern.-

Be it known that L ll Y L.

citizen of the United Floral T Sronnnr, a es, residing at Earl-t, lions; Island in the corn y of Nassau, State ot New York, have invented certain new and useful improvements in Machine Switching Telephone Exchange Systems of which the followingis a -full, clear, concise and exact description.

This invention relates to machine switch telephone exchange systems, and particularly to inulti-oiiice systems.

In a connection involving two stations lo cal to the otlice, satisfactory transmission is secured by feeding talking current to the transmitters through a pair oil. supervisory relays which may control the reiease of? the switches. ll hen however the connection leads through a number. of oflices" better transmission is secured by substituting tor this relay bridge. a repeating coil bridge.

.ln accordance with this invention the connectors are accessible to local second or third selectors, dependent upon the number of lines in the ol'lice in which the connectors located, and also to incoming selectors which are used when the call comes from or throu 'h adistant otlice. and the circuit arran ment is such that the path over which the connector is seized determines the character of the battery feeding arrangement to be used in enorgizing the transmitters ot' the connected lines.

'l 'he invention contemplates circuit arrangement wherein the electrical condition of the test wire of the selector seizing; such connector determines the operation 0t an electromagnetic switch connected to the test wire of the connector which controls the curren ;teedinn' bridges.

lilore specifically, when a connector is seized. by a selector serving; local calls only the bridges for feeding talking current through a pair of relays are left connected across the connector tall-ring conductors to energize the substationtransmitters ot the in case however. this connector i {substation apparatus a l o 7 As shown, in the present embodiment, the

third conductor from the preceding local selector is connected to the tree pole of the battery and when the connector is seized this third conductor is extended to the third conductor of the connector in which a relay is included. This relay thereupon operates and interposes a break in the circuitof a relay which would otherwise operate when the called party answers and cut off the local relay bridges. 11". however, the connector is seized by an incoiningselector from a distant oliice the relay referred to in the third conductor of the connector is shuntedrdue to the presence of ground on the third conductor leading from. such incoming; selector and, consequently upon the response of the called subscriber the bridge cut-oil relay reterred to operates and removes the supervisory i relay bridges normally connected across the connector talking; conductors and transfers the called line talking conductors to the repeating: coil bridge the incoming selector. 7

lie terriiug to the drawings, which show only so much of a telephone exchange systerm as is necessary for a comprehension of the invention, the connector C is located in the ollice to which the lines terminating in substations A and belong. The incoming selector sh 1 below selector S is also located in this office. The sender sills however, located at a distant o'l'lice. The connector group including connector C is multiplcd to the local selectors S and also to the incoming: selectors, so that it may be seized by a trunk from a distant otiice terminating in incoming selectors as well as locally by selectors S.

With this preliminary description it is believed that an understanding of' thefinvention will be n'iost easilyacouired by 'followinc; in detail the building upot'ai call of each class. A local connection will b traced;

Upon the removal oi receiver at. substation it, the calling linejis e itenfded oyfera series of switches in tlic well-ln to the selector iiis-itiprece'din' tor whereupon. the follow? closed: t'r'ee oole oi": battei fllet; inc; 03'? stepp'in relay ,1. 0t the soled tor, side switch. .arnr 2 "f'ositionIli l the lower tall ng' condticcoi, f tliroug'h, ;tl1e l re urning ver; the ion sideswtch arm upper talking condi 5, position 1, right Winding of stepping relay lto'ground. Relay l in en ergizing, operates slow relay 6, which, in at acting its armature, grounds the third Wire 7, leading back to the preceding switches to hold the sarne in their set posi tion, in accordance with Well-known practice, and operates release relay 8 to inter pose a break in the circuit of the release magnet not shown of the switch to which stepping relay l belongs. The calling sulr scrihern'ow operates sender to set selector S to the level of the trunks terrainating in connectors hereupon the. selector automatically hunts for and seizes an idle connector in the well-known rnanner. Upon the extension of the calling line to th connector, the side switch of selector S advances to position 3, cutting oil the bridgeincluding: relay lleiiore the slow relay 6 can retract its armature, however, the ping relay 10 of the connector is operated over the i'follovringcircuit: tree pole of battery, right winding of relay 10, lower arinature'and hack contact or relay 11, over ste the lower talking conductor to the calling substation and returning; over the upper talking conductor, upper armature of relay 11 and its back Contact, lettwindino; of relay 10 to ground llelay 10, in tracting its armature, operates slow relay 12, which, in attracting its right armature. connects the primary stepping magnet PM to the heel: contact of stepping relay l0, and in attracting its lett arinature operates relay 13 through the following circuit: ground, right Winding of relay 13, left armature of relay 12, conductors let, 15,16, to the free pole 'ofthe battery, through the Winding of r l 8. The left ari'nature ot relay 13 is arrai igecl to close front contac'- efore the right armature. lt thus loclrs itself over the lef armature of relay l2 and its own left and right armatures. The ground applied tothe third or test 1 e by the right armature oii relay 13 is applied before the slow relay 6 of: the preceding selector has had time to release and relay 8 thusheld ener ized. This ground causes the conneetor to test busy to other selectors.

The caning; subscriber now operates his sender to transmit impulses to the connector corresponding to the tens digit of the wanted number Upon the first retraction of the armature of relay 10, an unpulse is transmitted over the following;

w'rr ont Contact ofrelay l2, oil-normal. contact lfi lcontriollecl by" the connector shaft, slow i a gnet PM, free pole battery. at thebeginning oi tl movement ot the s1 norrnal contact 18 opens 4 ch19 clo s so cir :cuit, to operate the primary stepping magot the connector: armature and back Contact o relay l0, richt armature and When it operated, connected the stepping magnet to the back Contact at the stepping relay 10 over the contact 19 independently of contact 18. The subsequent impulses, therefore, pass by Way er contact 19 and the front contact'oi the-slow relay 17 to the magnet Phi, 51 short interval alter the magnet 10, armature and front contactot slow relay 12 Which as before, becomes enargizecl upon the receipt of the first impulse and remains energized during the transnission of the impulses, contact 19, armature and hack contact of sloiy relay l7, slow relay 20, lowermost 1 armature of relay 21, outer armature and baclr contact of relay 22, magnet SM and tree pole or battery. The subsequent impulses pass over the following path to operate magnet SM: armature and back contact of relay 10, right ar- :nature and front contact of relay 12, contact l9, ar nature and back contact of relay 1?, slow relay 20, lowermos a mature and back contact otrelay 21, aud'oyer the left armature and frontcontact or relay 20,, and V outer right armature of relay i i parallel magnet EM, tree pole of battery. 20, 111 attracting its right armature, maintains the test circuit open during units select; 11, W hen the sender its normal position, he brushes and 7 of the connector are in ensra rnent with the multiples 26, oi: the d 'ired line. conditio. a line is indicated by he it full potential upon the multiples 28. A

short interval after the conneitor is set, slow relay 2O retracts its arniatures and if the is idle the following; circuit closed a marginal testrela'a 21: free pole 01" ry, called line cut-oil relay 29. iriultiple ture and b; r con;

resistance indv I mature of relay 22, 4 grounded atthe rie'ht arlront contact of relay 12 Belay 21, in attracting one of its lower armatures which is arra d to rnalre contact be e the othersloc itself to the grounded d Wire through its lower indir Due to t} e circuit through his inding e relay'is to attract i s al ii rl saunaturesi In attracting: its ar ure lflit connects'thc grounded rest Wire'direc l to the test multiples 28' of the selected line. thus reducing the potential on such multiples to cause the same reset-r y to other connecact 1 lowe most aw eture,

and the sender, thus preventing the subscriber from transmitting any more impulses to the connector. Uponthe attraction of the ar1natures31, 32 of relay 21, the bell t substation is operated over the fol lowin circuit: ringing generator 33, lower winding of ringing cut-off relay 3e, armature of said relay, armature 32 of relay 21, brush 24, multiple 27, lower talking conducto'r the bell at the called station, upper talking conductor, multiple 26, brush 23, armature 31 of relay 21 and its front contact, upper armature of relay 34:. to ground. When the called party removes his receiver the ringing cut-oi relay 3 1 attracts its mature 39, closing a locking circuit includ ing its upper winding and the grounded third wire. This'relay, due to the increase in its magnetization from the current through the locking winding, attracts its remaining armatures, disconnecting the ringing current generator from the called line and substituting therefor the called supervisory relay 22. The called supervisory relay 22 is now operated over a called line circuit as follows: free pole of battery, left winding of relay 22. contact of. relay 11, lower talking conductor including armature 85 and front contact of relay 3 1 and armature 32 of relay 21 and its front con-" tact, brush 24, multiple 2?, lower talking conductor through the telephone apparatus at substation l3, upper talking" conductor, multiple 26. brush 23, armature 31 of relay 21 and its front contact, armature 37 of re lay 3 1 and its front contact, contact 38 of relay 11, rigrht winding of relay 22, armature 39 and front contact of relay 3 1, to the grounded third wire. The subscribers may now converse, talking current being" sup-plied toenergize the transmitter at the calling station through the calling" superx' isory relay l0, and to the transmitter ot the called station through the called supervi sory relay 22, the calling; and called ends of the connecting circuit being conductivcly separated and inductively connected by condensers 4C0 and 11 in accordance with wellknown practice.

Upon the replacement of the receiver by the calling party, relay 10 becomes deenernixed. resulting in the deenergization of slow relay 12. Relay 12 in releasing, opens the lot-hing circuit of relay 13 which in retracting its right armature, removes ground from the release wire leading back the preceding set switches whereupon they release. The removal of this ground from the test wire also causes the relay 31 to unlock whereupon the following circuit is closed tor the release magnet RM of the connector. Magnet RM, off-normal contact 42. lowermost armature of relay 34, and its contact, armstures and back contacts and 19 to ground Upon reach:

not shown, of the incoming purpose its normal position, off-normal contact s opened, opening the release circuit.

Assume now that the suhstation B is called from a distant office. The incoming selector having been reached over a number of selectors, not shown, is set by the sender 4.6 at the distant oflice to the level containing the trunk group in which the connectors C terminate. The selector thereupon seizes an idle one of these connectors. lhe circuits of the repeater and incoming; selector are not shown in detail. since they may be of any well known pe. (inly so much shown as necessary to comprehend the present invention. When the calling line is extended to the steppii relay l? of the repeater which n t he in the same ofiice as the called line B, this stepping relay operclosing a circuit including; slow relay e8 side switch arm 49 of the incoming selectapping relay 50 of the incom selecvtor, free pole of battery. lielay 50 oper sting, energizes a slow relay 52 which operates releaserelay 5% thereof to interpose a break in the circuit of the release magnet, selector to pre vent premature release. The impulses for setting the incoming selector pass oyer the path just traced including tie right armature and front contact of relay the slow relay L8 and the stepping relay 50. iVhen the sole or seizes an idle connector t. the .lllCOE'l'll; selector side switch asses to the third position, the steppiw reay is cut off and the right-hand grounded armature and front contact oft-he repeating relay 1'? is extended to the talking brush 55 of the selector. The side switch arm 72 reaches its third position and connects the grounded armature of relay 59 to the release relay 5 1 before the ground which initially energized this relay is I'QIYlOVQfl by the release or slow relay 52 due the cutting off of stepping re ay 50 from the lower talking conductor. Ground from the armature of relay 59 is, in the third position of the side switch, extended over arm 73 to the third or test crush and thence to the third wire of the connector to cause the same to test busy to testing selectors. This ground also shunts relay 13 to prevent its energization for a which will appear. The testing circu ts for the selectors are not shown. They may he of the type shown in Patent No. 1,236858 of August let, 1917. ll hen the connector is seiner the stepping relay 10 thereof becomes energized over the following circuit: free pole of battery, right winding of relay 10, lower armature of relay 11, talking conductor 45, multiple 5?, brush 55. arm 4-9, slow relay as to the armature and front contact of relay 47, When the calling party transmits the tens impulses thecon' ec r is set in perative relation to the level e 1;; lesired line;

, attracting its lowermost armature,

larly when the units impulses are transmitted. the connector is set on the desired line multiples 26, and 28. These operations are the same as previous? described excent that the relay 10 is operated overone sideot' the line from the right armature or" relay l? instead of over a metallic circuit.

The ringing of the bell at the called station'B occurs. as previously described in the case of the local call, but in this case for relay ll is as follows: tree pole of ba tery, RM which is mar inal and a: does not operate in this circuit, oil-normal contact as, lowermost armature front contact of relay 3%, lower winding of relay ll, to ground through the armature and back contact of relay l3. Relay ll, in attracting its armaturcs, disconnects t bridges including the relays 10*and 22, and extends the calling: line directly through to the connector talking; brushes 23, 24;. Relay Set, by interposes a break in the circuit of release magnet BM before the slow relay 12 has time to retract its armatures when the relay .0 is cut ofi. Battery is now. fed to the called line from the repeating coil over the following circuit: free pole of battery, lower winding of retardation coil 75. windin 's 76 77 lower,

talking conductor, outer armature of relay 51, which operated when relay 48 became inertdue to the cutting off 01 the connector stepping relay 10 from the lower talking a conductor. side switch arin L9 talking brush 5f fret '55 multiple 5'1 conductor 56. lower talking conductor 45 of the conn ctor, lower armatureand front contact of relay 11, arnia ture 35 and front contact of relay 34$, armature 32 and front contact otrelay 21, brush 24, multiple 27', the called line B, multiple 26, brush 23. armature 31 and front contact relay 21, upper armature and front contact of relay 34%. upper armature front,

contact of relay llJconductorsAtat. 65, multiple 66 of the incoming selector, brush 67, side switch arm 68, inner armature and front contact of relay 5i, windings 78, 79'

upper retardation coil winding of the repeater to ground.

VVhen the calling party permanently opens the calling; line circuit upon the conclusion of the conversation relay 4'? becomes ineru This results in the deenergization of slow relay 59. which in removing ground from the third wire leading to the connector, un-

loclrs'ringi ut-oti' relay 3%. This relay,

lowermost armature closes circuit otthe release relay 54 of the circuit of release magnet RM or" the connector including the .armatures and back contacts of relays l0 and 12; hen the connector restores. off-normal contact as is opened to ,deenergize the release magnet. The deenergization of relay 59 in removing ground from the third wire also opens the the selector whereupon release of the selector .ltes place;

The operation of the circuit arrangement in case the called h s B is busy. will now be described. It will be recalled that the slow relay 20 is in series with the secondary stepping}; magnet SM of the connector and is maintained encrgizedduring the transmission of the secondary impulses. Upon the termination of these impulses however, this relay after an interyalyretracts its armatures. If the selected line is busy its .iultiple 28 is grounded due to the connection of agrounded test brush 25 at another connector, or to ground thereon from the line finderor other equivalent switch in case it is busy as a calling line. Before relay 20 has time to retract its armatures. however, the following circuit is closed to operate we lay 22 to apply busy tone to the calling line: grounded multiple 28, brush 25, right armature and front contact of relay 20, conductor 80, upper non-inductive winding of relay ll, contact 81 otrelay now closed contact36 of relay ill; le'llt winding of relay 22, free pole of battery. Relay 22 immediate y upon energization. looks itself up over the followinscircuit: tree pole of battery. relay 22, contact 36 ot-relay ll. contact 81, upper winding of relay 11, contact 83 of relay 2C, inner right armature of relay 22, to the grounded third wire. The middle armature of relay 22 applies busy tone to the calling line in the well-known manner. Test relay 21 does not operate in case the line is busy, since by the time the right armature of relay 20 is fully retracted relay in attracting its inner right armature has opened. the

energizing circuit of such relay, thus pre to this busy line. Upon the replacement of the receiver by the calling: party theswitches are released. It the call was a local call from substation A to substation B, the replacement of the receiverby the calling party results in the deenergization of relays l0 and 12 whereupon the switches are restored as previously described in the case ofa successful connection. In the case of an incomins; call involving the incoming selector. it will be recalled that thebridge containing the stepping relay 1O the. connector is not cut off until the called subscriber responds. Relay 10 is thus operated and is holding slow relay l2 energized and relay .12 is maintaining a break in the circuit'of release magnet RM. 7 Upon hearing the busy tone, the calling paipy at the distant and at the connection including the sender 4L6, breaks down the connection, thus releasing repeating relay his relay, in retracting its right armature, opens the circuit of step ping relay 10 of the connector, which in retracting its arn'iature, opens the circuit of slow relay 12. This relay, after an interal, closesits right back contact whereupon release magnet RM of the connector is en ergized over the following circuit: right armatures and back contacts of relays 10 and 12, lowermost armature of relay 34;, offnormal contact 42, magnet BM, free pole of battery. The retraction of the left armature of relay 47 opens the circuit of release relay 5% of the incoming selector, which thereupon restores.

.lt will thus be seen that by virtue of the present invention connectors of a given oitice may be accessible to both local calling lines and calling lines leading over or througn distant ofiices, and in each case the connector automatically adapts itself to the particular class of call being set up, in the one case feeding current to the local lines through supervisory relays, and in the other case cutting off these relays and extending a current feeding and transmission circuit arrangement to the called line which is more suitable for long distant calls.

What is claimed is:

1. in a machine switching telephone on change system, the combination with talking trunk conductors, an automatic switch wherein said trunk conductors terminate, a battery and feed coils normally bridged across said talking conductors at said switch, of an electromagnetic switch controlling the connection of said battery and feed coils to said conductors, a plurality of paths over which said automatic switch may be selected, means controlled by the path over which said switch is selected for con trolling the operation of said electromagnetic switch, a second bridge for feeding talking current, and means actuated when the first bridge is cut off for connecting said second bridge to said trunk conouctors.

2. in a machine switching telephone exchange system, talking trunk conductors, an automatic switch in which said conductors terminate having feed coils and a battery, normally connected to said cons ductors, said automatic switch being reached by a plurality of paths, and means for removing said feed coils and battery from said conductors, said means being controlled by the path over which the automatic switch is reached, a bridge for feed ing talking current to said trunk conductors, and means actuated when said feed coils and battery are disconnected from said con ductors for connecting said bridge thereto.

3. In a machine switching telephone can change system, a calling and a called line,

any

controlling the connection of said feed coil and battery to said conductors, the operation of said switch being dependent upon the selector used in extending the connection to the connector, a bridge for feeding talking current to said trunk conductors including a repeating coil, and means actuated when said feed coil and battery are disconnected for substituting said bridge.

4:. In a machine switching telephone er:- change system, a connector, a plurality of selectors for seizing the same a feed coil and a battery at said connector, a relay nor mally connecting said coil and battery to the talking conductors of said connector, said relay being operated to disconnect the same only when the connector is seized by certain of said selectors, and a bridge at said last mentioned selectors for feeding talking current to said trunk conductors, including a repeating coil substituted for saic feed coil by the operation of said relay.

5. In a machine switching telephone ex change system, telephone lines, a connector, a plurality of selectorsfor seizing the same, a pair of condensers, a battery and a pair of supervisory relays at said connector, one on each side of said condensers through which talking current is fed from said hat I tery to the connected lines, an electromagnetic switch normally connecting said battery and relays across the talking conductors of said connector, the operation of said switch being dependent upon the selector employed in extending the connection to the connector, a bridge for feeding talking current to said trunk conductors, said electromagnetic switch in operating to cut off said supervisory relays, substituting said bridge therefor.

6. In a machine switching telephone exchange system, a connector, a local selector, an incoming selector, a bridge at said in coming selector having a pair of condensers and a repeating coil, a pair of battery feed coils at said connector normally connected across the connector talking conductors, and a relay operated in case the connector is seized by said incoming selector for disconnecting said feed coils and substituting said bridge and forextendi. the talking conductors of said selector directly through to the connector brushes.

7. In a machine switching telephone exchange system, telephone lines, a connector, a talking battery, a local selector, an incoming selector, pair of feedcoils through which said battery is connected to the talking conductors of said connector, a switching relay for cutting off said coils, a circuit therefor closed when the called party re sponds, a second relay controlling at a back contact said circuit said second relay being included in the test conductor of said connector, and an energizing circuit for said second relay closed only When said con nector is seized by said local selector to prevent operation of said switching relay; upon the response of the called party.

In Witness whereof, I hereunto subscribe 10 my name this 24th day of November A. D, 1919.

RAY L. STOKELY. 

